Brief successive temporal observational sampling as a possible indicator of daily overt seizure activity in epileptic rats

Chronic, limbic epilepsy was induced in male rats by a single systemic inje ction of lithium and pilocarpine, In two separate experiments. each 6 mo. i n duration, the proportion of the population that displayed an overt motor seizure (head nodding, rearing, and forelimb clonus) within 10 min. each da y after delivery of food pellets (despite food provided ad libitum) was rec orded. Cumulative records Cor the numbers of rats in each population that d isplayed overt seizure for the first rime during the observation period wer e plotted as a function of lime. The occurrence of the saturated (approachi ng 100%) asymptote at about five months nas interpreted to indicate that br ief (10 min.) sampling over the 144 successive days that would compose a si ngle 24-hr, period could serve as an estimate of the average probability of an overt seizure during an average 24-hr. period. Ii this assumption is co rrect, then these rats would have displayed about one overt seizure per day .